Purpose of the study. To study the mitochondrial membrane potential, indicators of the enzymatic and non-enzymatic antioxidant systems, and the mtDNA damage index in the mitochondria of colorectal cancer (CRC) cells depending on its location, the presence of metastases in the lymph nodes, and the patient sex.

Patients and methods. The study included results obtained from 132 patients (52 women and 80 men) with T2-3N0M0 colon cancer. Mitochondria from intestinal and tumor tissue cells were isolated using differential centrifugation. The concentration of SOD-2, 8OHdG, vitamins A and E, GPO-1, and the membrane potential (ΔψM) were determined in mitochondria. Statistical analysis was performed using the program Statistica 10.0.

Results. In rectal tumor mitochondria with lymph node metastases, both men and women demonstrated increased 8-OHdG levels and decreased ΔψM compared with patients without lymph node metastases: in men, by 2.2-fold and 1.5-fold (p < 0.05), and in women, by 1.3-fold (p < 0.05) and 2.0-fold, respectively. In the left colon, tumor mitochondria in men with metastases showed a 2.4-fold increase in 8-OHdG, while ΔψM and vitamins A and E levels were reduced by 1.7-fold (p < 0.05), 2.4-fold, and 3.1-fold, respectively. In women, lymph node metastases were associated with decreased levels of vitamins A and E by 1.7-fold (p < 0.05) and 4.3-fold. In the right colon, tumor mitochondria in patients with metastases showed higher levels of vitamins A and E compared with those without metastases: vitamin A increased by 1.7-fold (p < 0.05) in men and 2.4-fold in women, and vitamin E by 4.2-fold and 3.9-fold, respectively. SOD-2 levels were 2.2-fold lower only in tumor mitochondria with metastases in men.

Conclusion. Mitochondrial oxidative stress is an important systemic phenomenon in progressive CRC, and its manifestations depend on patient sex and location.

Purpose of the study. To perform a comparative analysis of colorectal cancer (CRC) incidence trends in Russia and the Republic of Crimea from 2015 to 2024.

Materials and methods. Data from the medical statistics reports of the Federal State Statistics Service Administration for the Republic of Crimea and the city of Sevastopol, as well as average annual population data, were analyzed. Data processing was performed using Microsoft Office Excel. Mathematical analysis of trends was carried out using a linear model with calculation of the approximation reliability coefficient R² (R²min > 0.75).

Results. In the Republic of Crimea the figures for the period 2015–2024 are lower than the national figures, with the exception of 2022, and there has been an increase in the percentage of morphological verification and a decrease in the percentage of mortality within 1 year. The most concerning issue is the low detection rate of CRC during preventive examinations: from 10.4 % (colon cancer) and 16.5 % (rectosigmoid junction, rectum, and anus cancer) in 2015 to the current rates of 3.7 % and 8.6 %, respectively. In the Russian Federation, there has been an annual increase in this indicator, and in 2024, it reached 17.4 % and 19.8 % for these localizations. The detection rates of the disease at stages 1–2 in the Republic of Crimea are lower than the national rates (48.4 % and 51.6 %, respectively).

Conclusion. In the Republic of Crimea, the statistics on the incidence of CRC have changed over the past 8 years, depending on the organizational measures taken (due to the periods of the pandemic and improvements in the quality of care after 2014), and have shown a downward trend. Implementing early CRC diagnosis during preventive examinations is an important aspect of healthcare planning in the region.

Purpose of the study. To analyze the effectiveness of combined treatment for rectal cancer and evaluate the impact of ileostomy closure timing on treatment outcomes.

Patients and methods. A study of treatment outcomes in 250 patients with locally advanced rectal cancer was conducted to assess the influence of patient age, sex, tumor characteristics, and timing of ileostomy closure. From January 2020 to November 2025, patients underwent treatment and follow-up including radiotherapy with a total focal dose of 50–54 Gy combined with capecitabine- based radiosensitization, followed by low anterior resection of the rectum with preventive ileostomy formation.

Results. A significant prognostic factor has been established – metastatic involvement of regional lymph nodes (pN2), which increases the risk of death by 3.6 times (p = 0.0001) and the risk of disease progression by 4.1 times (p = 0.0004). Factors such as patients' age, gender, distance from the lower edge of the tumor, the degree of differentiation, and tumor invasion into the colon wall did not show a significant impact on overall survival and progression-free survival rates, which may be due to the limitations of the study (recruitment of a homogeneous group of patients with uniform treatment). No significant differences were found in overall survival rates (p = 0.9573) and progression-free survival rates (p = 0.5278) between groups of patients with ileostomy closure within 2 months and more than 4 months after low anterior resection of the rectum. Closure of the ileostomy within 2 months was accompanied by a decrease in the total number of postoperative complications (p < 0.001), parastomal hernias (p = 0.004), elevated creatinine levels (p = 0.037), the incidence of diversion colitis (p < 0.001), and diarrhea (p = 0.001).

Conclusion. The study confirmed the safety of the approach to closing the ileostomy within 2 months after radical surgery before the start of adjuvant chemotherapy in the combined treatment of rectal cancer. Early closure of the ileostomy is recommended in patients without involvement of regional lymph nodes (pN0) or with involvement of regional lymph nodes (pN1) in the absence of clinical and radiological signs of colorectal anastomosis insufficiency.

The recurrence rate within 12 months after surgery for pancreatic cancer (PCa) reaches 48 %. The concept of "futile sur gery" emphasizes that performing surgery without prior risk stratification not only fails to improve the prognosis but also increases the incidence of complications and reduces quality of life.

Purpose of the study. To analyze current data on criteria for early recurrence of PCa, their prognostic significance, and potential use as a tool for selecting patients for surgical treatment.

Materials and methods. A search was conducted in PubMed, Scopus, Web of Science, and Elibrary.ru from January 2019 to March 2026. The following keywords were used: "pancreatic ductal adenocarcinoma", "early recurrence", "futile surgery", "CA 19-9", "neoadjuvant therapy", "predictive model", "staging laparoscopy". Cohort studies, meta-analyses, systematic reviews, and clinical guidelines were included; isolated case reports, small series (<10 patients), experimental studies, and publications without a clear definition of early recurrence were excluded.

Results. The most significant preoperative predictors of early recurrence were elevated CA 19-9 levels (cutoffs from 97 to 210 U/mL), tumor size >3 cm, lymph node metastases, R1 resection, low grade of differentiation (G3), and the absence of adjuvant chemotherapy. Prognostic scores were developed and validated to stratify the risk of "futile surgery".

Conclusion. Early recurrence is a marker of "futile surgery". Multidisciplinary assessment using prognostic models, staging laparoscopy, and neoadjuvant therapy allows us to identify a high-risk group in which avoiding primary surgery does not worsen the prognosis but reduces the incidence of complications and improves quality of life. Further development of this approach requires prospective validation of existing scoring systems and the introduction of molecular genetic markers.

Primary hepatic neuroendocrine carcinoma is an extremely small proportion of all malignant tumors of this organ. Ac cording to published data, their proportion does not exceed 0.46 % among primary malignant liver neoplasms. Although well-differentiated primary hepatic neuroendocrine neoplasms are characterized by slow growth, poorly differentiated neuroendocrine carcinomas of the liver represent a distinct subgroup with inherently aggressive behavior. The diagnosis of such neoplasms is challenging due to the absence of specific imaging features and their similarity to hepatocellular carcinoma, cholangiocellular carcinoma, and metastatic liver lesions.

This article presents a case of primary neuroendocrine carcinoma of the liver (PNCL) in a 73-year-old patient. The comorbid background included chronic hepatitis B, type 2 diabetes mellitus, and liver cirrhosis. The tumor was incidentally detected during routine abdominal computed tomography. Over an 82-day observation period, rapid enlargement of the primary lesion from 42 to 95 mm was documented, along with progression of tumor thrombosis into the portal and hepatic veins and the development of distant lymphogenous metastases, including involvement of a cervical lymph node. Morphological verification was performed using biopsy material obtained from the cervical lymph node. The Ki-67 index exceeded 90 %, corresponding to the small-cell variant of poorly differentiated neuroendocrine carcinoma according to the 2019 WHO classification. The patient died on day 82 after the initial diagnosis before scheduled systemic chemotherapy could be administered.

The presented case demonstrates the potential for aggressive clinical behavior of PNCL even in the absence of features typical of hepatocellular carcinoma. Clinicians should consider PNCL in the differential diagnosis of rapidly progressive liver tumors and promptly pursue morphological verification of the diagnosis.

Primary gastric non- Hodgkin lymphomas represent the most common extranodal localization of lymphoproliferative disorders. The current standard of care, first-line immunochemotherapy based on rituximab (R-CHOP and CHOP-like reg imens), demonstrates high efficacy, achieving complete response in the majority of patients. However, 8–25 % of patients develop local life-threatening complications during or after treatment, among which gastric outlet obstruction (pyloric stenosis) is the most common. In routine clinical practice, elective surgical intervention is generally not performed in patients with lymphomas because these tumors are highly sensitive to systemic drug therapy.

This article presents a clinical case of a 49-year-old patient with stage IV extranodal B-cell gastric lymphoma and HIV-positive status, demonstrating the role of palliative surgical intervention. Despite achieving a partial metabolic response to polychemotherapy (EPOCH/R-CHOP regimens), the patient developed decompensated cicatricial- tumorous pyloric stenosis. This complication required active surgical management. Gastrojejunostomy was successfully performed as a palliative procedure, creating a bypass for gastric emptying into the jejunum while circumventing the obstruction site, which significantly improved the patient's quality of life. The postoperative course was uneventful, and no signs of progression of the underlying lymphoproliferative disease were observed during long-term follow-up. An additional advantage of the selected surgical approach was the rapid restoration of the patient's nutritional status while preserving oral feeding.

The presented clinical case confirms the feasibility of an individualized approach to the selection of palliative treatment strategies in patients with complicated gastric lymphoma.

Peritoneal carcinomatosis in advanced ovarian cancer is an unfavorable prognostic factor and limits the efficacy of systemic chemotherapy. This provides a rationale for the use of locoregional treatment modalities, including pressurized intraperitoneal aerosol chemotherapy (PIPAC). Of particular interest is the safety of a bidirectional strategy (systemic chemotherapy + PIPAC) in patients requiring multivisceral resection.

We present a clinical case of a patient with advanced ovarian cancer and peritoneal carcinomatosis. Induction bidirectional chemotherapy was administered, consisting of paclitaxel/carboplatin (6 cycles) combined with PIPAC using cisplatin 30 mg/m² (50 mg), 30-minute exposure, 3 sessions, followed by multivisceral cytoreductive surgery. Efficacy was assessed based on tumor marker dynamics, peritoneal cancer index (PCI), and morphological response (TRG), while safety was evaluated according to perioperative complications and the feasibility of continuing PIPAC after surgery.

At initial laparoscopy in April 2025, peritoneal carcinomatosis was detected (PCI 26); the first PIPAC session was performed, followed by systemic chemotherapy. After the second cycle, a partial response was documented. In June 2025, multivisceral cytoreductive surgery was performed, including anterior resection of the rectum with sigmoid stoma formation. Systemic therapy was resumed early and completed up to 6 cycles. By 20.08.2025, tumor markers had decreased: CA-125 to 47 U/mL, CA 19–9 to 13.7 U/mL, and HE-4 to 120 U/mL. Before PIPAC-2 (September 2025), no macroscopic carcinomato sis was detected (PCI 0); no tumor cells were found in peritoneal biopsy specimens, corresponding to TRG 1. At PIPAC-3 (November 2025), PCI remained 0, and repeat biopsies also corresponded to TRG 1.

Induction bidirectional chemotherapy including PIPAC in a patient with advanced ovarian cancer and peritoneal carcinomatosis demonstrated clinical feasibility, safety and marked antitumor efficacy even after multivisceral cytoreduction.